Development and trifoliin A-binding ability of the capsule of Rhizobium trifolii

J E Sherwood, J M Vasse, F B Dazzo, G L Truchet
1984 Journal of Bacteriology  
The age-dependent lectin-binding ability of Rhizobium trifolii 0403 capsular polysaccharide (CPS) was examined by following the development of the capsule and its ability to interact with the white clover lectin trifoliin A. Bacteria grown on agar plates for 3, 5, 7, 14, and 21 days were examined by electron microscopy and immunofluorescence microscopy with antibodies prepared against either R. trifolii 0403 CPS or trifoliin A after pretreatment with the lectin. The capsule began to develop at
more » ... egan to develop at one pole by day 3 and completely surrounded the cells in cultures incubated for 5 days or longer. The capsular polysaccharide on cells cultured for 3 and 5 days was completely reactive with trifoliin A, became noticeably less reactive by day 7, and was only reactive with the lectin at one pole of a few cells after that time. The quantity and location of lectin receptors on bacteria of different ages directly correlated with their attachment in short-term clover root hair-binding studies. Cells from 3-or 21-day-old cultures attached almost exclusively in a polar fashion, whereas cells grown for 5 days attached to root hairs randomly and in the highest numbers. CPS isolated from a 5-day-old culture had higher lectin-binding ability than CPS from 3and 7-day-old cultures, whereas the CPS from a 14-day-old culture had the lowest. Chemical analyses of the isolated CPS showed changes in the levels of uronic acids (as glucuronic acid), pyruvate, and 0-acetyl substitutions with culture age, but the neutral sugar composition remained relatively constant. These results provide evidence that the age-dependent distribution of lectin receptors dictates the level and orientation of attachment of R. trifolii 0403 to clover root hairs. R. trifolii 0403 for (i) the development of the capsule, (ii) the ability of the capsule at various stages of development to interact with the lectin, and (iii) the effect of culture age on the binding of the cells to clover root hairs. MATERIALS AND METHODS Bacterial cultures. R. trijolii 0403 was obtained from the Rothamsted Experimental Station (Harpenden, England). Cultures were maintained on Bll agar medium (10) and grown at 30°C. Broth cultures were grown in Bll medium as previously described (21). All transfers were made with a 5day-old plate culture as inoculum. on May 7, 2020 by guest
doi:10.1128/jb.159.1.145-152.1984 fatcat:omzvhqe43vclpbkfhrbteeqg6m